This invention relates to a lidded plastic barrel comprised of a barrel body covered by a barrel lid with a gasket insert and a clamping ring as specified in patent claim 1. A similar lidded barrel has been described earlier for instance in U.S. Pat. No. 5,427,264.
In a conventional lidded plastic barrel the lid gasket is held in place between the vertical outer side wall and the vertical inner ring of the lid (ref. FIG. 2). In drop tests (=dropping the barrel) and internal-pressure tests the central panel area of the lid tends to bend upwards, causing the vertical inner ring of the lid to bend inwards and upwards from its vertical position which in turn removes the pressure from the gasket, breaking the seal between the gasket and the barrel rim and leading to possible leaks in particularly affected locations.
It is the objective of this invention to introduce a lidded barrel of the general type referred to, in which a reinforced junction between the barrel lid and the rim of the barrel mouth provides an improved seal especially when exposed to high internal pressure or when the barrel is dropped (pressure surge on impact).
In the lidded barrel according to this invention, the barrel lid is provided within its U-channel-shaped rim with an additional rotationally symmectric sealing web, the gasket is positioned between the outer circular side wall of the lid and the sealing web, an annular recess between the sealing web and the inner circular side wall of the lid opens toward the bottom, and the sealing web and the inner side wall of the lid are spaced apart and mutually connected only via an upper flange. With this desirable enhancement, the barrel lid offers a distinct improvement over prior-art designs in that even in the case of substantial deformation of the vertical inner ring of the lid, bending it inwards and upwards, the sealing web remains vertical so that the pressure on the seal is not eased. Indeed, the vertical web bounding on the inner face of the gasket inherently provides better axial and radial retention of the gasket, so that, given less deformation in the area of the seal, it securely seals the barrel lid on the rim of the barrel mouth even under conditions of extreme impact on the lidded barrel.
In a variation of the proposed solution, the bottom surface of the lid is provided in juxtaposition to the inner, circular, peripheral side wall with a reinforcing element extending in the circumferential direction and having a self-contained cross section that is either hollow or foam-filled. This hollow or foam-filled reinforcing element may be formed by gas injection at the time the molten plastic is injected into the mold. Alternatively, the reinforcing element may be in the form of a separate, prefabricated, circular, hollow, self-contained plastic part that is fused to the barrel lid. By means of this torsion-resistant reinforcing element around the perimeter of the barrel lid, inserting and supporting itself on the inside of the barrel mouth, a deformation of the lid will not relieve the pressure on the lid gasket to a point beyond an acceptable level that would break the seal. In an enhanced design version of the invention, the upper inside rim of the barrel mouth is provided, in addition to and at a short distance from the circular sealing web, with a vertical upright, circular ridge which, when the barrel lid is mounted and closed, engages in the annular recess between the sealing web and the inner circular side wall of the lid. Thus, even if the inner ring of the lid is substantially deformed, the additional vertical sealing web is no longer exposed to possible inward or upward deformation since on the upper barrel rim the added vertical ridge reaches behind the additional vertical sealing web, firmly supporting it. When the barrel lid is mounted, closed and clamped tight by means of a ring, the upright vertical ridge and the downward-pointing sealing web overlap by at least 5 mm. The upright circular ridge may be in the: form of spaced-apart segments or of a continuous annular profile in which latter case it is preferably provided at its base with a perforation through which any possibly present liquid can drain off.
In a preferred embodiment, the recess between the sealing web and the inner annular side wall holds an additional circular gasket which, in the closed state of the barrel lid against the upper edge of the upright, circular ridge, provides a supplementary seal between the rim of the barrel mouth and that of the barrel lid. This further enhances the sealing capacity in the event of an extreme impact.
The lidded barrel according to this invention additionally offers the following significant features and advantages:
the additional vertical circular ridge profile on the barrel body consists of partly spaced segments, forming gaps through which water can drain off;
the additional vertical circular ridge is elongated so as to provide enhanced support to the added vertical sealing web;
in conjunction with a gasket in the barrel lid the additional, vertical, circular ridge on the barrel body supplements the seal between the barrel lid and the rim of the barrel mouth;
the connecting flange of the inner lid panel on the inside of the U-channel-shaped lid perimeter is positioned at or below the level of the lower edge of the outer side wall of the lid;
the connection of the inner lid panel to the inside of the U-channeled lid perimeter is made by way of a an essentially U-shaped, flat-base grasping groove, open towards the top, with the height of the inner lid panel or at least the central area of the lid panel being essentially aligned with, or protruding upwards beyond, the elevational plane of the upper lid perimeter.